Hold very tightly, please, ladies and gentlemen. The announcement of the winner of the mayor of London's competition for the design of a new London bus, or Mk 2 Routemaster, is just around the corner. Here's one of the designs - an electric double-decker called the e21, powered by rechargeable batteries - submitted by Michael Kerz, a graduate of Central St Martin's School of Art and Design.

Given that the original Routemaster, one of the finest of all city buses, appeared at a time when diesel oil was a lot cheaper than it is today, perhaps it's right that a new generation RM should be electric. But, just as the much-missed Routemaster has long been seen as a tourist attraction, so Kerz's design plays on the fact; his e21 boasts a full length transparent roof so tourists can gawp at passing pediments, plane trees and pigeons as Londoners flick through newspapers, grimace along to the thumpa-whompa-tss-tss-tss of personal stereos, doze, eat, drink and fight.

Like the Mk 1 Routemaster, Kerz's Mk 2 sports an open rear platform, beloved by generations of Londoners, but condemned by Transport for London officials as being too dangerous. An automatic safety barrier would keep would-be leapers in control until the bus had stopped, but surely this undermines the very nature of an open platform: the chance to get on and off anywhere along central London's congested streets, no faster than they were in the days of horse-drawn buses.

Kerz, as you can see has tried to borrow something of the Routemaster's profile, but it must be said that the e21 does look just a little angular and brutal compared with the functional elegance of the gently curved original. With its big whizzy wheels and aggressive, cartoon-like stance, the e21 looks better suited to Wacky Races than Route 11.

Next week, we should find out what Transport for London's judges feel about designs from Kerz, other design students, architects - including Norman Foster, whose entry just happens to resemble a trolleybus - engineers, industrial designers and others. The panel, it's good to know, is 100 per cent celebrity-free and composed wholly of those who, if the new bus does go ahead, will run it in daily service.

I suggest that the winning design ought to be in the spirit of the Routemaster and its predecessors, stretching back to the London General B-Type double-decker of 1910, but may well look nothing like it. A true a successor to the Routemaster should be a truly modern city bus designed for a long and trouble-free life and as energy and space efficient as technically possible.

A new Routemaster mustn't be fashionable and it cannot be aimed primarily at the tourist market. It has to be at least 10 times better looking than contemporary London buses, which are bought off the shelf. It doesn't need video screens inside (please not; surely Londoners can still read or simply enjoy looking out of the window?). It needs a quiet engine, however powered, as well as silent brakes. Oh, and it needs a grown-up interior design - unlike 99 per cent of contemporary London buses.

Most of all, the RM2 must be a London bus. London is one of the richest cities in the world, supposedly one of the most creative, and together we must find a way to commission a bus that, one day, will be as famous and as respected as the original Routemaster. We'll soon find out.